In 1925, R.A. Fisher (1890–1962) reconstructed Pearson’s notation, introducing Y = a + bX (the general equation for a straight line) and incorporating the terms “dependent” variable and “independent” variable. This was an essential distinction to make for regression, because the independent variable is the predictor and the dependent variable is the criterion. Fisher then produced the equation for the regression (or predicted) line: Y’ = a + bX (where b is the regression coefficient and Y’, pronounced “Y prime”, indicates a regression line).
